Heat indicator



April 0- R. EVANS ET AL 2,196,201

' I HEAT INDICATOR Filed Nov. 13, 1937 Fig.1., FT; 2.,

Fig5 I Fige Q 21 7 an 21 s2 2O Fig.7 5O

, Ml 4-1 v INVENTOR j ATTORNEY Patented Apr. 9, 1940 S PATENT OFFICE HEAT INDICATOR Ralph 1. 1mm, Bay Shore, and: Everett G.

. MoDonongh, Yonkers, N. Y.

Application November 13, 1937, Serial No. 174,426

16 Claims.

Our invention relates to the art of permanent when this danger point is reached for each indiwaving of hair and more particularly to means and methods whereby the critical ranges of temperatures during the hair waving operation are indicated to the operator.

In ermanently waving hair on the human head the hair is divided into a number of tresses, say from 25 to 60, and each tress is wettedwith a conditioning solution to enable it to take a permanent set, the tress is wound around a mandrel, the mandrel and tress being held by a clamp, and then heated to about 212 F. over the period of time required toeffect the wave. The waving heat may be derived from any convenient source, such as an exothermic mixture, an electric heater unit, a preheated metal mass, steam supplied through a tube from a suitable boiler, a suitably disposed electrolyte or metal wire or strip through which a current is passed to generate heat by its resistance, etc.

Although timing devices have been employed to indicate to the operator the duration of the waving period these have not been responsive to actual temperature conditions and heretofore it has been diilicult for the operator to determine when thelwaving zone of temperatures at the tress is actually reached, how long it has actually continued or when it has actually terminated. It occasionally happens that through some failure of a heater its hair waving period is too short, or it never gets up to hair waving temperature at all, and frequently these facts are not discovered until all the hair is taken down, when it is found to be necessary to take time to rewave the faulty tress or tresses. Again, the hair waving period may be too long due to over-heating, causing all the waving solution to be driven out and resulting in a poor wave and injury to, or even destruction of, the hair. These problems are further complicated by the fact that the operator, for best results, should be immediately apprised of these abnormal conditions-not merely for one heater unit-but for some 25 to units on a single head. A timing device can only approximate average conditions for all units and is incapable, not only of indicating actual conditions for any unit, but, much more, for each one of a plurality of individual units.

Moreover. in some systems, it is necessary to apply the heating unit'after the generation of heat has been initiated but before it has reached a temperature high enough to burn the operator's fingers and it is therefore desirable to ascertain vidual unit. I

All of these problems have been solved by our invention which is applicable to all hair waving systems.

In the exothermic machineless process, for example, heatis generated by the chemical contained in a small envelope, the chemical reaction being conveniently initiated by the introduction of water, carried by an absorbent, through the 10 perforations of an envelope containing the chemical. The chemical is so formulated that with the generation of heat there is a definite relationship established between temperature and time; that is, the average pad on a strand of hair has a necessary time-temperature relationship. For example, the low temperatures (below F.) during the first 45 to 60 seconds after wetting of the chemical gives the operator ample time to adjust the pad about the hair. The temperature during the next 30 seconds quickly rises to 212 F., the boiling point of water. Actual fast setting and permanent setting of the hair begins to take place at about 180 F. but the most permanent eflect in the snortesttime is accomplished at about 212 F. The temperature of the pad remains at this value for about 4 or 5 minutes and the pad then gradually begins to cool down to room temperature passing out of the eflective waving zone in about 15 minutes after the wetting of the chemical, the time in the eifective waving zone being about 13 to 15 minutes. The pads are removed when they have reached room temperature, then the hair is taken off the mandrel.

At the present time this method has proved commercially satisfactory in spite of the disadvantages inherent in it as well as in other systems, noted, all of which are due to the fact that the operatorhas no way of determining how the heat development is taking place. 00- casionally; a pad does not develop heat sufficient to raise the hair to the temperature of the permanent waving zone. Also it is difllcult for the operator to determine just when to remove the heating pad. If it isremoved too soon the hair has not received the proper permanent set. If it is left on unnecessarily long, the operator has lost valuable time and caused her patron needless 5o discomfort. The operator attempts to follow the course of the reaction by feeling the pads but it is obvious that this method is 'both time-consuming, inconvenient and uncomfortable both to operator and patron, as well as unsatisfactory, u

since it is difficult to Judge high temperatures by lightly touching a hot object with the finger tips. Moreover, since there are between 25 to 60 pads on a single head it is extremely difficult, if not impossible, for the operator to check them all.

By our invention the operator can determine just when the effective waving temperature is reached, the duration of time in the waving temperature zone and the proper moment when she can and should remove the pad or other heater.

This result is accomplished by the use of certain heat indicators which are brought into propinquity to or into contact with the pad, or heater, or clamp, or other part of the heater system capable of proportionately indicating the temperature ranges at the tress. These heat indicators are materials which change color or form, or state, or other noticeable characteristic at predetermined temperatures.

As an example of change in form, certain substances such as cobalt salts, e. g., cobalt chloride, change color when they lose their water of crystallization, this being easily and quickly accomplised at 212 F.

' As an example of change of state, most substances are opaque when solid but are transparent or translucent when liquid. By the selection of the proper substance or percentage of mixture of substances, as for example waxes, oil or fat, opaque solids can be obtained which melt and become liquid at any desired temperature. As a specific example, carnauba wax alone melts at about 185 F. By emperically varying the proportions of castor oil and carnauba wax, mixtures changing from opaque solids to transparent liquids at any temperature ranging from 185 F. to room temperature can be obtained. Coloring these mixtures with any coloring agent, such as oil-soluble colors (e. g., 2% of an oil-soluble Red or lakes, e. g., 5% of a Scarlet lake, makes the transition from the dull opaque solid to the brilliant light-reflecting and transmitting liquid more apparent. One of the most effective ways is to apply a spot of the uncolored opaque solid over a colored spot on the back of an exothermic pad, for instance. The opaque solid hides the color, but the light transmission of the liquid formed at higher temperatures allows it to be seen.

However, because of its simplicity, efllciency and adaptability, we prefer in most situations to use substances not dependent upon a change of state or a color change due to loss of water of crystallization or the like, but upon a color change, due, say, to internal molecular or atomic rearrangement. For example, white zinc oxide becomes yellow at high temperatures, and the iodides of mercury, copper and silver, and particularly mixtures of these metallic iodides, will change in color at relatively low temperatures.

As a practical embodiment of our invention, we have found that when we grind together- Parts Mercuric iodide 200 Cuprous iodide Water 200 filter, and then dry, we get a particularly effective pigment. This pigment when incorporated into the proper vehicles, such as printers varnish, can very conveniently be printed on the paper backing of the envelope containing the heat-generating chemical, or it can be applied directly to the surfaces of heating systems generally.

The course of the temperature development can then be followed by the color changeof this printed pigment on the paper (or other heater surface). The color of the pigment at low temperatures, that is, from room temperature to about F.'is an orange-red. At about this temperature, the orange-red color begins to darken, indicating to the operator that the pad is too hot to be safely handled and that it is beginning to function as a hair waving agency, and by the time the pad reaches 200 F. the color has changed to a deep mahogany (almost black) shade. This color persists as long as the pad re mains above F., indicating to the operator the duration of time in the waving zone. When the pad begins to cool and passes below this temperature the color gradually shades off and the orange-red color reappears at about 175 F. This re-appearance of the orange-red color tells the operator that-the pad can safely be removed since the temperature is now below the effective waving zone and has reached a point where the operator's fingers will not be burned.

Thus the operator has a visible means of determining just how the pad is functioning. At a glance, she can see if any pad on the head (there are usually about 30) has reached the effective waving zone. If the pad appears to be slow or ineffective she can determine the cause or replace it with a more effective one. The old method of guessing often failed to locate these ineffective pads, and it was not until the hair was unwrapped that it became evident from the lack of curl that the pad had not reached the waving zone. By comparison of colors with pads put on at the same time, it becomes obvious at once whether a pad remains in the waving zone sufliciently long, i. e., if the color remained mahogany black for the required time.

One of the mostimportant advantages in our invention lies in the fact that it saves the operators time and causes the patron no unnecessary discomfort; the moment the red color reappears, the pad can be removed without affecting the character of the wave. Removal of the pad at this fairly high temperature results in saving time, varying from 10 to 25 minutes. Also the failure of the mahogany color to be replaced by the red color, indicates that the chemical has generated too much heat and the temperature has gone too high and that the pad should be removed before damage to the hair occurs.

It is obvious that our invention can be applied in many different ways. For instance, the pigment may be attached to the hair clamping device, or to the clamps used to hold the pads about the hair, or on a separate instrument touching the pad or a part of the hair waving device, or to the surface of any heater systems, but in every instance the temperature development due to the heat generating means is followed by changes in the color of the pigment and this serves as visible means for aiding the operator to give a better, easier, and faster permanent wave.

Other novel features and advantages of our invention will hereafter appear.

Without limiting our invention or claims thereto, the accompanying drawing shows for purposes of exemplification, certain special embodiments of our invention.

Fig. 1 is a plan view of an exothermic pad provided with one form of our heat indicator at room temperature;

Fig. 2 shows the same pad as it appears when heated to hair waving temperature as'indicated by'the change in color of the indicator;

Fig. 3 is a vertical section on the line 3-3 of Fig. 4 shows a tress of hair wound on a mandrel, a clamp for holding the parts together, a heater and our heat indicator applied at one end of the mandrel;

Fig. 5 shows our heat indicating material applied to a separate strip or the like of suitable material such as strip metal which may be pressed about any desired part of the hair waving system;

- Fig. 6 is a plan view of an exothermic pad carrying a separate disk indicator secured thereto thermic material 2 enclosed in an envelope 3 so constructed as to permit introduction of water to initiate the heat generating reaction in a manner well known in the art. Printed or painted ing zone, about 180 F., the color becomes a mahogany black, as shown in Fig. 2, indicating to the operator that the hair waving zone has been reached. As long as the temperature remains in the hair waving zone the color remains unchanged but when the temperature drops, say, to

190 F., at'which temperature waving substantially ceases, the color gradually changes until at about 175 F. the original orange-red color reap-'- pears. The operator is thus able to follow the progress of temperature changes merely by observing the heat indicator.

In Fig. 4 is shown a tress oi hair I I held at its roots by a clamp II, the trees being wound about a mandrel I! also held in final position by the clamp, the tress, being surrounded by a heater diagrammatically shown at It of any conventional form such as an exothermic pad, an electric heater, a steam heater, a pre-heated mass of metal, a pad containing an electrolyte through which a current is passed to generate heat, etc. a

The heat indicating material I I is shown applied by painting or the like to the uncovered end of the mandrel, in which position its view is unobstructed. In this form the heat indicator is capable of repeated use without substantial deterioration. The indicating material maybe applied to any other part of the apparatus whose temperature varies proportionately to that at the tress, .for should it be applied to a part that is normally, say, far above the hair waving temperature at the tress, such as the surface of an electric heater, for instance, must be in order to have the proper hair waving temperature at the tress, a composition is selected which will change color at the temperature of the heater that produces the proper'hair waving temperature at the tress, the temperature at the tress being of course the critical one which it is desired to determine and the indication of the heater temperature being merely incidental to that purpose.

In Fig. 5 is shown a form of indicator separate from the parts of the heater system but which is designed to be conveniently applied to any suitable portion thereof. In this figure the device is shown as a disk 20 cut out of suitable sheet material such as strip metal or the like. on which is painted the heat indicating composition as in previous examples, the-disk being conveniently provided with projecting extensions II which may be pressed about any suitable part of the heater system to hold it in place to indicate the temperature changes in the manner above set forth. Such separate indicator may, of course, take many forms and may be attached to the part whose temperature range is to be indicated .in many ways as by staples, heat conducting cement or the like. Such devices may take the form of a simple disk or other suitable geometric figure which would enable it to be stapled by the ordinary paper fastener to a relatively thin pad such as the exothermic pad or the electrolytic pad, the stapleextending either through the whole pad or through the backing alone. This construction is shown in Fig. 6 in which the disk is shown at 30, the pad at 3| and the staple at 32. It is to be noted that the indicator should bemounted on that portion of the pad which will be within easy view of the operator when the pad is mounted around the tress. In Fig. '7 is shown a spring clip provided over its outer surface, or a portion thereof, with heat indicating material shown at ll, said clip being of a size and shape enabling it to be sprung about any suitable part of the heater system whose temperature varies proportionately to that at the hair.

Where materials which indicate the changes in temperature by the change of their form are employed, they may be'applied to the surface whose range of temperature is to be indicated in a manner similar to that already-described. For instance, crystals of cobalt chloride may be dissolved in a water soluble glue or gum acacia and painted .on the surface desired to be covered. When this mixture dries out, crystals of cobalt chloride remain attached to the surface and when subjected to a temperature of 212 F. are caused to lose their water of crystallization, accompanied by a change of color, therebyindicating that the hair waving zone has been reached. 1

Similarly, the range of hair waving temperatures may be indicated by materials whose change of state corresponds to the critical temperature to be indicated, in the manner already explained.

It will be understoodthat many changes may be made in the forms, features and materials disclosed without deviating from the spirit of our invention. 7

We claim: s

1. A temperature indicator for the permanent waving of hair including means maintaining its normal color until a hair waving temperature is reached, rapidly changing to another color at said temperature, and continuing to change its color progressively until the optimum hair waving temperature is reached, maintaining said color during the period of said optimum hair waving temperature, and, upon said temperature dropping I and continues to change its color progressively thereafter until the optimum hair waving temperature is reached, and as said temperature drops below said optimum value, changing its color in reverse order.

3. In a temperature indicator for the permanent waving oi' hair, means indicating by color changes the pre-waving temperature period, the duration of the waving temperature period. and

. the post-waving temperature period.

4. A temperature indicator for the permanent of hair including means maintaining its normal color until a hair waving temperature is reached and rapidly changing to another color at said temperature.

6. A temperature indicator for the permanent waving of hair including means which indicates by its color a hair waving temperature and which changes to another color immediately upon the temperature dropping below the hair wavin8 temperature and maintains said color as the pad cools.

6. A pad for permanently waving hair including color changing means for indicating development of hair waving temperatures by change from one color to another at approximately 190 F. 1

7. A pad i'or permanently waving hair including color-changing print for indicating temperature changes.

8. A pad for permanently waving hair including visible pigment indicating temperature change by color change.

9. A pad for permanently waving hair including mercuric iodide indicating temperature aiaaaoi waving of hair including means maintaining its normal condition until a hair waving temperature is reached, rapidly changing to another condition at said temperature, maintaining said condition during the period of hair waving temperatures, and, upon the temperature dropping below hair waving temperature returning to its original condition.

11. Means for permanently waving hair including means for indicating temperature change by its change oi state.

12. A temperature indicator for the permanent waving of hair by change of state comprising carnauba wax.

13. An indicator attachment for indicating change to hair waving temperature, including a material which changes color with temperature changes, and means for attaching said indicator to a hair waving system.

14. The method of permanently waving hair comprising subjecting the hair to heat and indicating development and duration of eilective hair-waving temperature with a color-changing pigment.

15. The method of permanently waving hair comprising subjecting the hair to heat generated by exothermic chemical and indicating development and duration oi eiiective hair-waving temperature with a color-changing pigment.

16. The method of permanently waving hair comprising subjecting the hair to heat generated by exothermic chemical and indicating development and duration oi effective hair-waving temperature with a color-changing pigment containing mercuric iodide.

RALPH L. EVANS. EVERETT G. McDONOUGH. 

